RAID system with external hardrives@Bob I am saying that on Mountain Lion Time Machine will spread the backups across both drives. I do not know the algorithm used to do the spreading. I just know that TM can use more than one drive.

Mount NFS share in /Volumes as a drive@CatalinM the /etc/fstab file does not exist by default. You have to create it. See this Apple document for more info, specifically page 9 where it describes fstab and how autofs interacts with fstab. And please up-vote my answer if you found it useful